Mix the sugar and cinnamon well (this will help the cinnamon not to form lumps).
Heat the rest of the milk with the sugar until hot and the sugar has dissolved. Remove from heat, add the gelatin and stir until dissolved.
Divide mixture into ramekins and refrigerate for 4-6 hours or until firm to the touch.
In a small glass, mix corn flour and water.
When the berries start to boil, add 1 tablespoon of the corn flour mixture and stir until mixture is glossy. If you want the sauce more thick add the rest of the corn flour and stir again for 1-2 minutes. Remove from heat and let cool.